Three dimensional semiconductor integrated circuit having gate pick-up line and method of manufacturing the same

ABSTRACT

A 3D semiconductor integrated circuit having a gate pick-up line and a method of manufacturing the same, wherein the semiconductor integrated circuit includes a plurality of active pillars formed in a gate pick-up region, buffer layers formed on the respective active pillars in the gate pick-up region, gates each surrounding an outer circumference of the corresponding active pillar and the corresponding buffer layer, and a gate pick-up line electrically coupled to the gates.

CROSS-REFERENCES TO RELATED APPLICATION

This application claims priority under 35 U.S.C. 119(a) to Koreanapplication No. 10-2014-0037800, filed on Mar. 31, 2014, which isincorporated by reference in its entirety as set forth in full.

BACKGROUND

1. Technical Field

Various embodiments of the present invention relate to athree-dimensional (3D) semiconductor integrated circuit and a method ofmanufacturing the same, and more particularly, to a 3D semiconductorintegrated circuit capable of improving gate pick-up failures, and amethod of manufacturing the same.

2. Related Art

With the rapid development of mobile and digital informationcommunication and the consumer-electronic industry, studies on existingelectronic charge controlled-devices may encounter limitations. Toovercome the limitations, new functional memory devices having noveldesigns need to be developed. Particularly, next-generation memorydevices with large capacities, ultra-high speed and ultra-low power needto be developed to satisfy demands of large capacity memories used inmain information devices.

Resistive memory devices using a resistance material as a memory mediumhave been suggested as the next-generation memory devices, and typicalexamples of resistive memory devices are phase-change random accessmemories (PCRAMs), resistance RAMs (ReRAMs), or magnetic RAMs (MRAMs).

A resistive memory device may be typically formed of a switching deviceand a resistance device and may store data “0” or “1,” according to astate of the resistance device.

A final target of the resistive memory devices is to improve integrationdensity and to integrate as many memory cells as possible in a limitedsmall area. In recent years, methods of forming the resistive memorydevices into 3D structures have been also suggested, and there is agrowing need for a method of stably stacking a plurality of memory cellshaving narrower line width.

A typical method of manufacturing a resistive memory device having a 3Dstructure includes a method of forming a switching device using avertical pillar as a vertical channel layer.

The 3D channel structure having a vertical pillar, has a verticalsurround gate. The vertical surround gate structure may be formed tosurround a lower region of the pillar. The vertical surround gates mayform a gate pick-up in a predetermined region. The gate pick-up line maybe electrically contacted to the gate using a general contact process.Since the gate is formed to surround a circumference of a lower portionof the pillar, an over-etching process is used to form a contact hole(hereinafter, referred to as a gate pick-up hole) for forming the gatepick-up line.

However, when using the over-etching process, the contact hole maypenetrate a substrate region (for example, source region) located belowthe pillar, and thus a short circuit between the gate pick-up line andthe substrate portion (for example, source region) of the pillar, may becaused.

As described above, as the gate is formed to surround the circumferenceof the lower portion of the pillar, the contact hole for forming thegate pick-up line also has a depth approaching a height of the pillar.Therefore, an aspect ratio of the contact hole in which the gate pick-upline is formed is increased, and thus a void may occur in the gatepick-up line.

SUMMARY

According to an embodiment of the present invention, there is provided asemiconductor integrated circuit. The semiconductor integrated circuitmay include a plurality of active pillars formed in a gate pick-upregion, buffer layers formed on the respective active pillars in thegate pick-up region, gates each surrounding an outer circumference ofthe corresponding active pillar and the corresponding buffer layer, anda gate pick-up line electrically coupled to the gate.

According to an embodiment of the present invention, there is provided asemiconductor integrated circuit, wherein the semiconductor integratedcircuit may include a semiconductor substrate having a cell array regionand a gate pick-up region which include a plurality of pillars,respectively, buffer layers formed on the respective pillars included inthe gate pick-up region, first gates formed on an outer circumference ofthe respective pillars included in the cell array region, second gateseach surrounding an outer circumference of the corresponding pillar andthe corresponding buffer layer included in the gate pick-up region, anda gate pick-up line electrically coupled to the second gates.

According to another embodiment of the present invention, there isprovided a method of manufacturing a semiconductor integrated circuit.The method may include forming a buffer layer on a semiconductorsubstrate including a cell array region and a gate pick-up region,etching a predetermined portion of the buffer layer and thesemiconductor substrate to form a plurality of pillars, forming firstgates each surrounding a circumference of the respective pillarsincluded in the cell array region, and second gates each surrounding acircumference of the respective pillars and the etched buffer layerincluded in the gate pick-up region, forming an insulating layer on thesemiconductor substrate in which the first gate and the second gate areformed, forming a gate pick-up hole to expose the buffer layer and thesecond gates in the gate pick-up region, and filling a conductive layerin the gate pick-up hole to form a gate pick-up line.

These and other features, aspects, and embodiments are described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thesubject matter of the present disclosure will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIGS. 1 to 4 are cross-sectional views illustrating a method ofmanufacturing a semiconductor integrated circuit according to anembodiment of the present invention;

FIG. 5 is a cross-sectional view illustrating a semiconductor integratedcircuit according to another embodiment of the present invention;

FIG. 6 is a block diagram illustrating a microprocessor according to anembodiment of the present invention;

FIG. 7 is a block diagram illustrating a processor according to anembodiment of the present invention; and

FIG. 8 is a block diagram illustrating a system according to anembodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, various exemplary embodiments will be described in greaterdetail with reference to the accompanying drawings. Exemplaryembodiments are described herein with reference to cross-sectionalillustrations that are schematic illustrations of exemplary embodiments(and intermediate structures). As such, variations from the shapes ofthe illustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, exemplary embodimentsshould not be construed as limited to the particular shapes of regionsillustrated herein but may include deviations in shapes that result, forexample, from manufacturing. In the drawings, lengths and sizes oflayers and regions may be exaggerated for clarity. Like referencenumerals in the drawings denote like elements. It is also understoodthat when a layer is referred to as being “on” another layer orsubstrate, it can be directly on the other or substrate, or interveninglayers may also be present. It is also noted that in this specification,“connected/coupled” refers to one component not only directly couplinganother component but also indirectly coupling another component throughan intermediate component. In addition, a singular form may include aplural form as long as it is not specifically mentioned in a sentence.

Embodiments according to the present invention are described herein withreference to cross-section and/or plan illustrations that are schematicillustrations of preferred embodiments of the present invention.However, embodiments of the present invention should not be limitedconstrued as limited to the present invention. Although a fewembodiments of the present invention will be shown and described, itwill be appreciated by those of ordinary skill in the art that changesmay be made in these exemplary embodiments without departing from theprinciples and spirit of the present invention.

Referring to FIG. 1, a silicon oxide layer 105 and a buffer layer 110are sequentially deposited on a semiconductor substrate 100. Thesemiconductor substrate 100 shown in FIG. 1 may be, for example, a cellarray region including a gate pick-up region. An “X” region in FIG. 1may illustrate a cross-section in a direction substantiallyperpendicular to an extending direction of a gate line to be formedlater, and a “Y” region may illustrate a cross-section in a directionsubstantially parallel to the extending direction of the gate line. Thebuffer layer 110 may include a silicon nitride layer or a layer havingetching selectivity to a silicon oxide layer. The buffer layer 110 mayinclude a polysilicon layer. A hard mask pattern 115 for defining apillar 120 is formed on the buffer layer 110. The hard mask pattern 115may include, for example, a silicon nitride layer. The buffer layer 110,the silicon oxide layer 105, and the semiconductor substrate 100 areetched using the hard mask pattern 115 to form an active pillar 120. Asan etching method for forming the pillar 120, an anisotropic etchingmethod may be used. However, a sidewall of the pillar may have a tapedform due to an aspect ratio of the pillar. The pillar 120 may be, forexample, a junction region of a transistor, that is, a source and adrain.

A gate insulating layer 125 is covered on an outer wall of the activepillar 120 and an outer wall of the buffer layer 110. The gateinsulating layer 125 may be formed of, for example, a dual layerincluding a silicon oxide layer 130 and a silicon nitride layer 135. Thesilicon oxide layer 130 may be formed, for example, through a thermaloxidation method.

A gate material layer 140 is formed to surround the pillar 120 on whichthe gate insulating layer 125 is covered. The gate material layer 140may be formed of, for example, a conductive layer such as a Ti/TiNlayer, but the gate material layer is not limited thereto. The gatematerial layer 140 in the X-direction may be shown to an outer wallspacer shape of the pillar 120. The gate material layer 140 in theY-direction may be formed in a form to be filled in a space betweenpillars 120.

The semiconductor substrate 100 exposed by the gate material layer 140is further etched to a certain depth in the X region. A gap-fillinsulating layer 145 is formed to be sufficiently buried in the etchedsemiconductor substrate. The gap-fill insulating layer 145 may include,for example, a spin on dielectric (SOD) material. The gap-fillinsulating layer 145 may penetrate the inside of the semiconductorsubstrate 100 between the pillars 120 to obtain sufficient nodeisolation.

Referring to FIG. 2, the gap-fill insulating layer 145 is planarizeduntil the hard mask pattern 115 is exposed. A mask pattern 150 is formedon a formed on a gate pick-up region GP in the Y region.

Referring to FIG. 3, the hard mask layer 115, the gap-fill insulatinglayer 145, and the gate material layer 140 of the cell array regionother than the gate pick-up region GP are recessed to a certain depthusing the mask pattern 150. After the mask pattern 150 is removed, thehard mask pattern 115 of the gate pick-up region GP is selectivelyremoved.

The gate material layer 140 of the gate pick-up region GP may be left ina form to be buried in the entire space between the pillars 120, and thegate material layer 140 of the cell array region other than the gatepick-up region may be left in a lower portion of the space between thepillars 120. The gate is defined by the recess process.

Referring to FIG. 4, a silicon oxide layer 152 is formed on an exposedgate material layer 140 shown in FIG. 3, and the gate pick-up region GP.The buffer layer 110 and the silicon oxide layer 105 shown in FIG. 3, ofthe cell array region other than the gate pick-up region are selectivelyremoved. Thus, an upper region of the active pillar 120 may be opened. Adrain D may be formed on the upper region of the active pillar 120 by anion implantation. An ohmic layer 155 may be formed on the upper regionof the active pillar 120 in which the drain D is formed. For example,the ohmic layer 155 may be formed to cover the upper region of theactive pillar 120. The ohmic layer 155 may include, for example, a metallayer of Ti/TiN. However, the ohmic layer 155 is not limited thereto,and various conductive layers may be provided as the ohmic layer 155. Aninterlayer insulating layer 160 may be formed on the semiconductorsubstrate 100 in which the ohmic layer 155 is formed. The interlayerinsulating layer 160 may include a plurality of insulating layers. Forexample, the interlayer insulating layer 160 in the space between thepillars 120 may be formed of a silicon nitride layer, and the interlayerinsulating layer 160 other than the space may be formed of a siliconoxide layer.

The interlayer insulating layer 160 is etched to form a bit line hole BHand a gate pick-up hole GH. A conductive layer is buried in the bit linehole BH and the gate pick-up hole GH to form a bit line 165 and a gatepick-up line 170. The conductive layer constituting the bit line 165 andthe gate pick-up line 170 may be formed of a barrier metal layer and amain metal layer.

Referring to FIG. 5, a phase-change material layer PCM may be furtherinterposed between the ohmic layer 155 and the bit line 165.

Since the gate pick-up hole GH and the bit line hole BH aresubstantially formed in the same process, the gate pick-up hole GH maynot extend to the substrate 100, that is, to below the pillar 120, andis formed in the buffer layer 115 and the gate material layer 140 shownin FIG. 3. Therefore, a short circuit between the gate pick-up line 170and the pillar 120, for example, between the gate pick-up line 170 and acommon source line is prevented. Further, since an aspect ratio of thegate pick-up hole GH is reduced, the gate pick-up line 170 is easilyfilled.

As illustrated in FIG. 6, a microprocessor 1000 to which thesemiconductor device according to the embodiment of the presentinvention is applied may control and adjust a series of processes, whichreceive data from various external apparatuses, process the data, andtransmit processing results to the external apparatuses. Themicroprocessor 1000 may include a storage unit 1010, an operation unit1020, and a control unit 1030. The microprocessor 1000 may be a varietyof processing apparatuses, such as a central processing unit (CPU), agraphic processing unit (GPU), a digital signal processor (DSP), or anapplication processor (AP).

The storage unit 1010 may be a processor register or a register, and thestorage unit may be a unit that may store data in the microprocessor1000 and include a data register, an address register, and a floatingpoint register. The storage unit 1010 may include various registersother than the above-described registers. The storage unit 1010 maytemporarily store data to be operated in the operation unit 1020,resulting data processed in the operation unit 1020, and an address inwhich the data to be operated on, is stored.

The storage unit 1010 may include one of the semiconductor devicesaccording to embodiments of the present invention. The storage unit 1010including the semiconductor device according to the above-describedembodiment may have a structure in which a gate pick-up line is formedin a buffer layer without extension to the inside of a semiconductorsubstrate.

The operation unit 1020 may be a unit that may perform an operation inthe microprocessor 1000, and perform a variety of four fundamental rulesof an arithmetic operation or logic operations depending on a decryptionresult of a command in the control unit 1030. The operation unit 1020may include one or more arithmetic and logic units (ALUs).

The control unit 1030 may receive a signal from the storage unit 1010,the operation unit 1020, or an external apparatus of the microprocessor1000, performs extraction or decryption of a command, or input or outputcontrol, and executes a process in a program form.

The microprocessor 1000 according to the embodiment may further includea cache memory unit 1040 that may temporarily store data input from anexternal apparatus or data to be output to an external apparatus, otherthan the storage unit 1010. The cache memory unit 1040 may exchange datawith the storage unit 1010, the operation unit 1020, and the controlunit 1030 through a bus interface 1050.

As illustrated in FIG. 7, a processor 1100 to which the semiconductordevice according to the embodiment is applied may include variousfunctions to implement performance improvement and multi-functions, inaddition to the functions of the microprocessor that may control andadjust a series of processes, which receive data from various externalapparatuses, process the data, and transmit processing results to theexternal apparatuses. The processor 1100 may include a core unit 1110, acache memory unit 1120, and a bus interface 1130. The core unit 1110 inthe embodiment according to the present invention may be a unit that mayperform arithmetic and logic operations on data input from an externalapparatus, and include a storage unit 1111, an operation unit 1112, anda control unit 1113. The processor 1100 may be a variety of system onchips (SoCs) such as a multi core processor (MCP), a GPU, or an AP.

The storage unit 1111 may be a processor register or a register, and thestorage unit 1111 may be a unit that may store data in the processor1100 and include a data register, an address register, and a floatingpoint register. The storage unit 1111 may include various registersother than the above-described registers. The storage unit 1111 maytemporarily store data to be operated in the operation unit 1112,resulting data processed in the operation unit 1112, and an address inwhich the data to be operated on, is stored. The operation unit 1112 maybe a unit that may perform an operation in the processor 1100, andperform a variety of four fundamental rules of an arithmetic operationor logic operations depending on a decryption result of a command in thecontrol unit 1113. The operation unit 1112 may include one or morearithmetic and logic units (ALUs). The control unit 1113 receives asignal from the storage unit 1111, the operation unit 1112, or anexternal apparatus of the processor 1100, performs extraction ordecryption of a command, or input or output control, and executes aprocess in a program form.

The cache memory unit 1120 may be a unit that may temporarily store datato supplement a data processing rate of a low speed external apparatusunlike the high speed core unit 1110. The cache memory unit 1120 mayinclude a primary storage unit 1121, a secondary storage unit 1122, anda tertiary storage unit 1123. In general, the cache memory unit 1120 mayinclude the primary and secondary storage units 1121 and 1122. When ahigh capacity storage unit is needed, the cache memory unit 1120 mayinclude the tertiary storage unit 1123. The cache memory unit 1120 mayinclude more storage units. That is, the number of storage unitsincluded in the cache memory unit 1120 may be changed according todesign. Processing rates of data storage and discrimination of theprimary, secondary, and tertiary storage units 1121, 1122, and 1123 maybe the same as or different from each other. When the processing ratesof the storage units are different, the processing rate of the primarystorage unit is the greatest. One or more of the primary storage unit1121, the secondary storage unit 1122, and the tertiary storage unit1123 in the cache memory unit 1200 may include one of the semiconductordevices according to the embodiments of the present invention. The cachememory unit 1120 including the semiconductor device according to theabove-described embodiment may have a structure in which a gate pick-upline is formed in a buffer layer without extension to the inside of asemiconductor substrate. Further, FIG. 7 has illustrated that all theprimary, secondary, tertiary storage units 1121, 1122, and 1123 aredisposed in the cache memory unit 1120. However, all the primary,secondary, tertiary storage units 1121, 1122, and 1123 in the cachememory unit 1120 may be disposed outside the core unit 1110, and maysupplement a difference between the processing rates of the core unit1110 and an external apparatus. Further, the primary storage unit 1121of the cache memory unit 1120 may be located in the core unit 1110, andthe secondary storage unit 1122 and the tertiary storage unit 1123 maybe located outside the core unit 1110 to further enforce a function tocompensate a processing rate.

The bus interface 1130 may be a unit that may couple the core unit 1110and the cache memory unit 1120 to efficiently transmit data.

The processor 1100 according to the embodiment of the present inventionmay include a plurality of core units 1110, and the core units 1110 mayshare the cache memory unit 1120. The core units 1110 and the cachememory unit 1120 may be coupled through the bus interface 1130. The coreunits 1110 may have the same configuration as the above-described coreunit 1110. When the core units 1110 are provided, the primary storageunit 1121 of the cache memory unit 1120 may be disposed in each of thecore units 1110 corresponding to the number of core units 1110, and onesecondary storage unit 1122 and one tertiary storage unit 1123 may bedisposed outside the core units 1110 so that the core units share thesecondary and tertiary storage units through the bus interface 1130.Here, the processing rate of the primary storage unit 1121 may begreater than those of the secondary and tertiary storage units 1122 and1123.

The processor 1100 according to the embodiment may further include anembedded memory unit 1140 that may store data, a communication moduleunit 1150 that may transmit and receive data to and from an externalapparatus in a wired manner or a wireless manner, a memory control unit1160 that may drive an external storage device, and a media processingunit 1170 that may process data processed in the processor 1100 or datainput from an external input device, and may output a processing resultto an external interface device. The processor may further include aplurality of modules other than the above-described components. Theadditional modules may transmit data to and receive data from the coreunit 1110 and the cache memory unit 1120, and transmit and receive datatherebetween, through the bus interface 1130.

The embedded memory unit 1140 may include a volatile memory as well as anonvolatile memory. The volatile memory may include a dynamic randomaccess memory (DRAM), a mobile DRAM, a static RAM (SRAM), or the like,and the nonvolatile memory may include a read only memory (ROM), a NORflash memory, a NAND flash memory, a phase-change RAM (PCRAM), aresistance RAM (RRAM), a spin transfer torque RAM (STTRAM), a magneticRAM (MRAM), or the like. The semiconductor device according to theembodiment may also be applied to the embedded memory unit 1140.

The communication module unit 1150 may include all modules such as amodule coupled to a wired network and a module coupled to a wirelessnetwork. The wired network module may include a local area network(LAN), a universal serial bus (USB), Ethernet, power line communication(PLC), or the like, and the wireless network module may include InfraredData Association (IrDA), Code Division Multiple Access (CDMA), TimeDivision Multiple Access (TDMA), Frequency Division Multiple Access(FDMA), a wireless LAN, Zigbee, a Ubiquitous Sensor Network (USN),Bluetooth, Radio Frequency Identification (RFID), Long Term Evolution(LTE), Near Field Communication (NFC), Wireless Broadband Internet(Wibro), High Speed Downlink Packet Access (HSDPA), Wideband CDMA(WCDMA), Ultra WideBand (UWB), or the like.

The memory control unit 1160 may be a unit that may manage datatransmitted between the processor 1100 and an external storage apparatusthat may operate according to a different communication standard fromthe processor 1100. The memory control unit 1160 may include a varietyof memory controllers, or a controller that may control IntegratedDevice Electronics (IDE), Serial Advanced Technology Attachment (SATA),a Small Computer System Interface (SCSI), a Redundant Array ofIndependent Disks (RAID), a solid state disk (SSD), External SATA(eSATA), Personal Computer Memory Card International Association(PCMCIA), a USB, a secure digital (SD) card, a mini secure digital (mSD)card, a micro SD card, a secure digital high capacity (SDHC) card, amemory stick card, a smart media (SM) card, a multimedia card (MMC), anembedded MMC (eMMC), a compact flash (CF) card, or the like.

The media processing unit 1170 may be a unit that may process dataprocessed in the processor 1100 or data input from an external inputdevice, and may output a processing result to an external interfacedevice so that the processing result may be transferred in video, sound,or other types. The media processing unit 1170 may include a GPU, a DSP,a HD audio, a high definition multimedia interface (HDMI) controller, orthe like.

As illustrated in FIG. 8, a system 1200 to which the semiconductordevice according to an embodiment of the present invention is applied,is a data processing apparatus. The system 1200 may perform input,processing, output, communication, storage, and the like, to perform aseries of operations on data, and include a processor 1210, a mainstorage device 1220, an auxiliary storage device 1230, and an interfacedevice 1240. The system according to the embodiment may be a variety ofelectronic systems that may operate using a processor, such as acomputer, a server, a personal digital assistant (PDA), a portablecomputer, a web tablet, a wireless phone, a mobile phone, a smart phone,a digital music player, a portable multimedia player (PMP), a camera, aglobal positioning system (GPS), a video camera, a voice recorder,Telematics, an audio visual (AV) system, or a smart television.

The processor 1210 is a core configuration of the system that maycontrol interpretation of an input command and processing such as anoperation and comparison of data stored in the system, and may include aMPU, a CPU, a single/multi core processor, a GPU, an AP, a DSP, or thelike.

The main storage device 1220 is a storage area that may receive aprogram or data from the auxiliary storage device 1230 and execute theprogram or the data when the program is executed. The main storagedevice 1220 retains the stored contents even in power off, and mayinclude the semiconductor device according to the above-describedembodiment. The main storage device 1220 may have a structure in which agate pick-up line is formed in a buffer layer without extension to theinside of a semiconductor substrate.

The main storage device 1220 according to the embodiment may furtherinclude an SRAM or a DRAM of a volatile memory type in which allcontents are erased in power off. Alternatively, the main storage device1220 may not include the semiconductor device according to theembodiment but may include an SRAM or a DRAM of a volatile memory typein which all contents are erased in power off.

The auxiliary storage device 1230 is a storage device that may store aprogram code or data. The auxiliary storage device 1230 may have a lowerdata processing rate than the main storage device 1220, but may storelarge amounts of data and include the semiconductor device according tothe above-described embodiment. The auxiliary storage unit 1230 may havea structure in which a gate pick-up line is formed in a buffer layerwithout extension to the inside of a semiconductor substrate.

An area of the auxiliary storage device 1230 according to the embodimentmay be reduced, to reduce a size of the system 1200 and increaseportability of the system 1200. Further, the auxiliary storage device1230 may further include a data storage system (not shown), such as amagnetic tape or a magnetic disc using a magnetism, a laser disc usinglight, a magneto-optical disc using a magnetism and light, an SSD, a USBmemory, an SD card, an mSD card, a micro SD card, an SDHC card, a memorystick card, an SM card, an MMC, an eMMC, or a CF card. Alternatively,the auxiliary storage device 1230 may not include the semiconductordevice according to the above-described embodiment but may include adata storage system (not shown), such as a magnetic tape or a magneticdisc using a magnetism, a laser disc using light, a magneto-optical discusing a magnetism and light, an SSD, a USB memory, an SD card, an mSDcard, a micro SD card, an SDHC card, a memory stick card, an SM card, anMMC, an eMMC, or a CF card.

The interface device 1240 may exchange a command and data of an externalapparatus with the system of the embodiment, and may be a keypad, akeyboard, a mouse, a speaker, a microphone, a display, a variety ofHuman Interface Devices (HIDs), or a communication device. Thecommunication device may include all modules such as a module coupled toa wired network and a module coupled to a wireless network. The wirednetwork module may include a LAN, a USB, Ethernet, PLC, or the like, andthe wireless network module may include IrDA, CDMA, TDMA, FDMA, awireless LAN, Zigbee, a USN, Bluetooth, RFID, LTE, NFC, Wibro, HSDPA,WCDMA, UWB, or the like.

The above embodiments of the present invention are illustrative and notlimitative. Various alternatives and equivalents are possible. Theinvention is not limited by the embodiments described herein. Nor is theinvention limited to any specific type of semiconductor device. Otheradditions, subtractions, or modifications are obvious in view of thepresent disclosure and are intended to fall within the scope of theappended claims.

What is claimed is:
 1. A semiconductor integrated circuit comprising: aplurality of active pillars formed in a gate pick-up region; bufferlayers formed on the respective active pillars in the gate pick-upregion; gates each surrounding an outer circumference of thecorresponding active pillar and the corresponding buffer layer; and agate pick-up line electrically coupled to the gates, wherein the gatepick-up line is formed on the gates and the buffer layers.
 2. Thesemiconductor integrated circuit of claim 1, wherein the gate pick-upline is formed to extend toward an inside of the buffer layer.
 3. Thesemiconductor integrated circuit of claim 1, further comprising gateinsulating layers each formed between the respective active pillars andthe respective gates.
 4. The semiconductor integrated circuit of claim1, wherein adjacent buffer layers are insulated from each other.
 5. Asemiconductor integrated circuit comprising: a semiconductor substratehaving a cell array region and a gate pick-up region, which include aplurality of pillars, respectively; buffer layers formed on therespective pillars included in the gate pick-up region; first gatesformed on an outer circumference of the respective pillars included inthe cell array region; second gates each surrounding an outercircumference of the corresponding pillar and the corresponding bufferlayer included in the gate pick-up region; and a gate pick-up lineelectrically coupled to the second gates.
 6. The semiconductorintegrated circuit of claim 5, wherein the first gates have a heightlower than the pillar.
 7. The semiconductor integrated circuit of claim6, wherein the first gates surrounding adjacent pillars are insulatedfrom each other.
 8. The semiconductor integrated circuit of claim 5,further comprising drains formed on an upper region of the respectivepillars included in the cell array region.
 9. The semiconductorintegrated circuit of claim 8, further comprising ohmic layers formed onthe respective pillars included in the cell array region.
 10. Thesemiconductor integrated circuit of claim 9, wherein the ohmic layersinclude a conductive material layer.
 11. The semiconductor integratedcircuit of claim 9, further comprising bit lines each electricallycoupled to the corresponding drain and formed in the cell array region.12. The semiconductor integrated circuit of claim 11, further comprisingphase-change material layers each interposed between the correspondingdrain and the corresponding bit line.
 13. The semiconductor integratedcircuit of claim 5, further comprising gate insulating layers eachformed between the respective first gates and the respective pillars,and between the respective second gates and the respective pillars. 14.The semiconductor integrated circuit of claim 13, wherein the gateinsulating layers are interposed between the buffer layers and thesecond gates, respectively.
 15. The semiconductor integrated circuit ofclaim 15, wherein the buffer layers include a polysilicon layer.
 16. Amethod of manufacturing a semiconductor integrated circuit, the methodcomprising: forming a buffer layer on a semiconductor substrateincluding a cell array region and a gate pick-up region; etching apredetermined portion of the buffer layer and the semiconductorsubstrate to form a plurality of pillars; forming first gates eachsurrounding a circumference of the respective pillars included in thecell array region, and second gates each surrounding a circumference ofthe respective pillars and the etched buffer layer included in the gatepick-up region; forming an insulating layer on the semiconductorsubstrate in which the first gate and the second gate are formed;forming a gate pick-up hole to expose the buffer layer and the secondgates in the gate pick-up region; and filling a conductive layer in thegate pick-up hole to form a gate pick-up line.
 17. The method of claim16, further comprising: performing a recess process so that the firstgates are located to be lower than the pillar.
 18. The method of claim16, further comprising: forming drains on the respective pillarsincluded the cell array region.
 19. The method of claim 18, wherein,when the gate pick-up hole is formed in the gate pick-up region, a bitline hole is simultaneously formed in the cell array region, and whenthe gate pick-up line is formed in the gate pick-up region, bit linesare simultaneously formed in the cell array region.